when libmach is compiled with 6c, unions in the 32bit Uregs
cause fields to be wronly aligned. use #pragma pack arround
the #include "/$objtype/include/ureg.h" statement.
file offset is 64 bit signed integer, negative offsets
are invalid and rejected by the kernel. to still access
kernel memory on amd64, we unconditionally clear the sign
bit of the 64 bit offset in libmach and devproc sign
extends the offset back to a 64 bit address.
instructions like BKPT, BX and BLX. Decoding these correctly allows db/acid to
single step through BX and BLX on armv5t+, and to show a breakpoint instruction
as 'BKPT $#0' instead of 'TEQ R0@>R0,R0'.
From richard:
A couple of patches applied yesterday should make debugging on ARM a
bit more reliable. Using db or acid on ARM, you may have noticed that
a program being debugged would sometimes execute through a breakpoint
without stopping, or run away while being single stepped. It turns out,
as often happens, that one symptom had two separate causes. For details:
/n/sources/patch/applied/5db-condcode/readme
/n/sources/patch/applied/arm-bkpt-cond/readme
To take advantage of the patches, rebuild libmach.a, then acid and db.
On machines with a kw kernel (sheevaplug et al), you'll also want to
rebuild /arm/9plug; otherwise breakpoints will stop working at all.
The new 9plug will, however, still work with the old libmach; and
the bcm and teg2 kernels are already compatible with the new libmach.
we now always use the new FXSAVE format in FPsave structure and fpregs
file, converting back and forth in fpx87save() and fpx87restore().
document that fprestore() is a destructive operation now.
change fp register definition in libmach and adapt fpr() acid funciton.
avoid unneccesary copy of fpstate and fpsave in sysfork(). functions
including syscalls do not preserve the fp registers and copying fpstate
from the current process would mean we had to fpsave(&up->fpsave); first.
simply not doing it, new process starts in FPinit state.
